You can get a permit to backcountry camp instead of reserving a designated campground spot. Just walk down to the beach after check-in and walk east until you see a pole with a tent symbol on it. After that you can choose where you want to set up camp. There are many spots along the dunes and allows to really space out from other campers. It felt like we had the entire beach to ourselves because there was no one else even close to around us, we went the weekend after labor day.